Compressible fluid turbine

ABSTRACT

Centripetal blades of a compressible fluid turbine project into a scroll-like steam induction passage so that their tips lie at or near the tangential centerline of the passage inlet when each blade tip is disposed in a plane normal to such centerline. A pressure reducing valve in the inlet to the steam induction passage converts steam pressure into kinetic energy and is adjusted to produce a velocity of steam at the inlet which is substantially greater than the peripheral velocity of the blade. There is very little reaction effect of the steam on the centripetal blades as the steam is directed radially inwardly and then axially in opposite directions to axial flow portions of the turbine and, consequently, the efficiency of the turbine is increased.

United States Patent [72] Inventor Rudolf Hendriks FOREIGN PATENTSHengelo, Netherlands 829,179

[21] Appl. No. [22] Filed June 2, 1969 [45] Patented Oct. 5, 1971714,135 10/1931 France.................,....... 416/234 PrimaryExaminerHenry F. Raduazo AtmrneySnyder and Butrum [73] AssigneeKoniuklijke Machinefabriek Stork N. V. l-lengelo, Netherlands [32]Priority May-31, 1969 [33] Netherlands [31] 6807690 [54] COMPRESSIBLEFLUID TURBINE ABSTRACT: Centripetal blades of a compressible fluidturbine project into a scroll-like steam induction passage so that theirtips lie at or near the tangential centerline of the passage 6 Claims, 3Drawing Figs.

al to such centerline. A pressure reducing valve in the inlet to thesteam induction passage converts steam pressure into kinetic energy415/159, inlet when each blade tip is disposed in a plane norm and isadjusted to produce a velocity of steam at the inlet which issubstantially greater than the peripheral velocity of the blade. Thereis very little reaction effect of the steam on etal blades as the steamis directed radially inwardly and then axially in opposite directions toaxial flow portions of the turbine and, consequently, the efficiency ofthe d e S a e r C .w m U .E n e e C .m e m m m 3 8 l 1 0 3 wmmow w I l 105 5 10 l 04 4 ,O 3 4 0 0 mm n3 u "0 S u 4 m m T m m m9 N m n "5 m u n n2 mm m n "U C u m m Em m Q T n AW m m mr m m O m m RED m 6 w m m S H L m2 m m .m M .1 1 1 B 1 0 6 1 5 5 5 t l PATENTED OCT 5 I97! INVENTORRUDOLF HENDRIKS .JW we? m NEYS COMPRESSIBLE FLUID TURBINE BACKGROUND OFTHE INVENTION My copending application, Ser. No. 669,139, filed Sept. 201967, now U. S. Pat. No. 3,479,124, discloses a compressible fluidturbine arrangement having a centripetal steam induction portion inwhich the tips of the centripetal blades cooperate directly with ascroll-like steam induction passage. A pressure reducing valve at theinlet to the steam induction passage converts steam pressure intokinetic energy so that the steam enters the induction passage at highvelocity. This arrangement provides very high efficiencies by minimizingfriction losses incidental to the process of introducing the steamcentripetally and directing it into the power producing portions of theturbine.

BRIEF SUMMARY OF THE INVENTION I have found that if the blade tips ofthe centripetal petal wheel portion of a compressible fluid turbine areextended so as to lie at or near the extension of the centerline of thetangential inlet portion of the compressible fluid induction passage, avery sharp and further increase in efficiency is effected as comparedwith the arrangement disclosed in my above copending application. I havefurther found that the optimum positioning of the tips of thecentripetal blades with respect to an extension of the centerline of theinlet to the compressible fluid induction passage downstream of thepressure reducing valve may vary between relatively narrow limitsdependent upon the mass rate of flow of the compressible fluid to theturbine assembly. Thus, for low mass rates of flow, the tips of theblades may be disposed slightly above the centerline as much asapproximately 2 percent of the diameter of the centripetal petal wheelwhereas at high mass rate flows, the tips optimally may be positionedbelow the centerline by as much as approximately 20 percent of thecentripetal wheel diameter.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a vertical sectional viewtaken transversely through a turbine constructed according to thepresent invention:

FIG. 2 is a longitudinal sectional view taken substantially along theplane of section line 2-2 in FIG. 1, and

FIG. 3 is a diagrammatic view illustrating the range of disposition ofthe centripetal blade tips with respect to the axial centerlineextension of the inlet portion of the steam induction passage.

DETAILED DESCRIPTION OF THE INVENTION Referring specifically to thedrawing, more particularly to FIG. 2, the compressible fluid turbineshown is of the axial flow type and includes a rotor housed within acasing 12, the rotor 10 being provided with a centripetal wheel portion14 and, on opposite sides thereof, two series of axial flow blades 16and 18 which cooperate with fixed blades 20 and 22, respectively, thatare carried by the interior of the casing 12. The rotor 10 is joumaledwithin the casing 12 by any suitable means and is adapted for high-speedrotation relative thereto.

In the particular embodiment shown, as is seen in FIG. 1, a pair ofsteam induction passages 24 and 26 are diametrically disposed betweenthe rotor 10 and casing 12, said passages being of scroll-like form andrespectively having inlet portions 28 and 30 which have axialcenterlines 32 and 34 and discharge tangentially into the respectivepassages 24 and 26. The inlet portions 28 and 30 are provided withpressure reducing valve members 36 and 38, respectively, to convert thepressure of the steam supplied into kinetic energy so that the steamenters at relatively high velocities at the inlets to the passages 24and 26.

High-pressure steam inlets 40 and 42 communicate with the inlet portions28 and 30 and the valves 36 and 38 are of generally bulbous form so asto minimize friction losses. Automatic or other type of controlassemblies 44 and 46 may be as- LII sociated with the respective valves,serving to shift the valve members axially and form greater or lesserrestriction of the inlets 28 and 30 to control the mass rate of flow ofsteam entering the passages 24 and 26. Steam entering the passages 24and 26 is directed by the blades of the centripetal wheel 14 firstradially inwardly and then axially in opposite directions, as indicatedby the arrows 48 and 50 in FIG. 2, to flow through the axial flowportions of the turbine assembly and ultimately for discharge, asindicated by the arrows 52 and 54.

The individual blades 56 of the centripetal wheel 14 have paddleliketips located at or nearthe extensions 'of the centerlines 32 and 34 ofthe inlets 28 and 30 to the steam induction passages or chambers 24 and26, as, for example, is indicated with respect to the blade tips 58 wheneach individual blade is positioned so that its tip lies within a planenormal to the extension lines 32 or 34, as shown in FIG. 1.

l have discovered that there is a sharp increase in the efficiency ofthe turbine assembly if the blade tips are positioned to lie within arange spanning the respective centerlines. This range isdiagrammatically illustrated in FIG. 3 wherein the extension 32 of theaxial centerline of the inlet passage 28 is selected for representationrelative to axis 60 of rotation of the centripetal wheel 14. g

The limits of the range within which the blade tips must lie to achievethe markedly increased efficiency according to this invention arerepresented by the lines 62 and 66, the plane normal to the centerlineextension 32 being represented by the dashed line 64. The maximumdistance above centerline 32, that is the distance between the blade tipposition 62 and the centerline extension 32, may be as great as 2percent of the diameter of the centripetal wheel 14. The other end ofthe range, that is the low limit thereof, may be such as to locate theblade tip position 66 at a distance below the extension 32 by an amountas great as 10 percent of the diameter of the centripetal wheel.

With the foregoing relationships prevailing, and utilizing steampressures in the order of 10 to I00 atmospheres, it is necessary thatthe valves 36 and 38 effect a pressure reduction sufficient toestablish, at the inlets 28 and 30, an entrance velocity for the steamwhich is in the order of 1% to 3 times the peripheral velocity (i.e.,blade tip velocity) of the centripetal wheel 14. These relationshipsestablish high efficiencies for the turbine assembly inasmuch as thereis very little reaction effect at the centripetal wheel. There may be aslight negative reaction effect at low mass flow rate of steam and aminor amount of positive reaction at high flow rates of steam.

The mass flow rate of steam into the turbine is of course a function ofthe turbine design and an exact relation between the blade tip positionsand the centerline extension of the steam inlet cannot be established.However, low mass flow rates will dictate a position tending toward theposition 62 in FIG. 3 while high mass flow rates will tend toward theblade tip position 66 in FIG. 3.

To illustrate this, we can define a so-called specific mass flow numberm,.

where: F, total throat area of the valves (2,, critical velocity asgiven by local fluid conditions at the throat area. c,, speed of soundas given by fluid properties and static conditions at the throat area. w=specific weight of the fluid as given by the local fluid conditions atthe throat area. d =the diameter of the centripetal wheel. F, and a havethe same dimensions. I In practical embodiments of the invention at alow mass flow rate of m,#).00l(c,,) w maximum efficiency of the turbineoccurred with the blade tips positioned 0.02 d outwardly from thecenterline extension, whereas at a high flow rate of mF0.03 (c ,wmaximum efficiency was obtained with a blade tip location which was 0.10d inwardly from the centerline extension.

Thus, it will be appreciated that the specific construction shown inFIGS. 1 and 2 is intended to represent a turbine of the axial typeoperating at relatively high mass rates of flow, as evidenced by thefact that the blade tip extremities are positioned somewhat below thecenterline extension 32. Therefore, the ratio Fjd', where F is the totalcross-sectional area of the two inlet throats 28 and 30, is relativelylarge, i.e. it is closer to the value 0.03 than to the value 0.001 whichrepresent the extremes set forth above. In any event, it will beunderstood that the centripetal wheel of a compressible fluid turbineis, according to this invention, so constructed as described above thatlosses originating in the region of compressible fluid inlet leading tothe power producing portion or portions of the turbine are reduced,resulting in increased efficiency for the turbine assembly.

Although FIGS. 1 and 2 illustrate a preferred embodiment wherein twoinlets are employed, it will be appreciated that a greater or lessernumber of inlets is contemplated.

The construction according to the present invention can be expected toyield approximately 8 percent relative average increase in efficiency ascompared to the efficiency attained by a turbine constructed in accordwith the aforesaid copending application.

I claim: I

1. In a turbine assembly adapted to be driven by pressurizedcompressible fluid, said turbine assembly being of the type having acasing and a rotor within said casings; said rotor having a centripetalwh wheel portion presenting a series of centripetal blades havingpaddlelike tips; said casing also having a a chamber presenting chamberpaddlelike said blade tips and having an inlet portion with the crosssection of said chamber tips of each blade when positioned to be withina plane normal to said extension of the axial centerline of said inletportion terminates relative to said extension within a range extendingfrom 0.10 d inwardly of said extension to 0.02 d outwardly of saidextension, wherein d is the diameter of said wheel portion.

3. In the turbine assembly as defined in claim I wherein the velocity ofsaid driving fluid issuing through said discharge mouth is in the orderof one and one-half to three times I greater than the peripheralvelocity of said blade tips.

decreasing from said inlet portion circumferentially around said casing;said inlet portion being connected at one end to a source of drivingfluid and having a discharge mouth at its other end opening tangentiallyinto said chamber, the improvement comprising:

the tip of each centripetal blade being of radial extent to terminate inthe region of an extension of the axial centerline of said inlet portionwhen each blade tip is rotationally positioned to be within a planenormal to such extension, and regulating valve means in said inletportion for reducing the pressure of the driving fluid within said inletportion to produce a velocity of compressible driving fluid issuingthrough said discharge mouth into said chamber which is substantiallygreater than the peripheral velocity of said blade tips. 2. in theturbine assembly as defined in claim 1 wherein the 4. A turbine assemblyadapted to be driven by pressurized compressible fluid, comprising incombination,

an elongate casing having radially inwardly rotor stator blades,

a rotor within said casing, said rotor having radially projecting bladescooperating with said stator blades to convert axial flow of the drivingfluid into rotor rotation, said rotor also having a centripetal wheelportion, said wheel portion presenting a series of centripetal bladeshaving paddle like tips and root portions for directing radiallyincoming fluid in axial direction within said casing toward said statorblades,

said casing having a circumferentially extending portion presenting achamber receiving said blade tips, and said casmg also having an inletportion leading tangentially into said chamber, the cross section ofsaid chamber decreasing from said inlet portion circumferentially aroundsaid casing, said inlet portion being connected to a source of drivingfluid and having a discharge mouth at its inner end opening into saidchamber, said blade tips being of radial extent to terminate in theregion of an extension of the axial centerline of said discharge mouthwhen each blade tip is rotationally positioned to be withing a planenormal of such extension,

and regulating valve means in said inlet portion for reducing thepressure of the driving fluid within said inlet portion to produce avelocity of compressible driving fluid issuing through said dischargemouth into said chamber which is substantially greater than theperipheral velocity of said blade tips.

5. In the turbine assembly as defined in claim 4 wherein the tips ofeach blade when positioned to be within a plane normal to said extensionof the axial centerline of said inlet portion terminates relative tosaid extension within a range extending from 0.10 d inwardly of saidextension to 0.02 d outwardly of said extension, wherein d is thediameter of said wheel portion.

6. in the turbine assembly as defined in claim 5 wherein the velocity ofsaid driving fluid issuing through said discharge mouth is in the orderof one and one-half to three times greater than the peripheral velocityof said blade tips.

1. In a turbine assembly adapted to be driven by pressurizedcompressible fluid, said turbine assembly being of the type having acasing and a rotor within said casings; said rotor having a centripetalwh wheel portion presenting a series of centripetal blades havingpaddlelike tips; said casing also having a a chamber presenting chamberpaddlelike said blade tips and having an inlet portion with the crosssection of said chamber decreasing from said inlet portioncircumferentially around said casing; said inlet portion being connectedat one end to a source of driving fluid and having a discharge mouth atits other end opening tangentially into said chamber, the improvementcomprising: the tip of each centripetal blade being of radial extent toterminate in the region of an extension of the axial centerline of saidinlet portion when each blade tip is rotationally positioned to bewithin a plane normal to such extension, and regulating valve means insaid inlet portion for reducing the pressure of the driving fluid withinsaid inlet portion to produce a velocity of compressible driving fluidissuing Through said discharge mouth into said chamber which issubstantially greater than the peripheral velocity of said blade tips.2. In the turbine assembly as defined in claim 1 wherein the tips ofeach blade when positioned to be within a plane normal to said extensionof the axial centerline of said inlet portion terminates relative tosaid extension within a range extending from 0.10 d inwardly of saidextension to 0.02 d outwardly of said extension, wherein d is thediameter of said wheel portion.
 3. In the turbine assembly as defined inclaim 1 wherein the velocity of said driving fluid issuing through saiddischarge mouth is in the order of one and one-half to three timesgreater than the peripheral velocity of said blade tips.
 4. A turbineassembly adapted to be driven by pressurized compressible fluid,comprising in combination, an elongate casing having radially inwardlyrotor stator blades, a rotor within said casing, said rotor havingradially projecting blades cooperating with said stator blades toconvert axial flow of the driving fluid into rotor rotation, said rotoralso having a centripetal wheel portion, said wheel portion presenting aseries of centripetal blades having paddle like tips and root portionsfor directing radially incoming fluid in axial direction within saidcasing toward said stator blades, said casing having a circumferentiallyextending portion presenting a chamber receiving said blade tips, andsaid casing also having an inlet portion leading tangentially into saidchamber, the cross section of said chamber decreasing from said inletportion circumferentially around said casing, said inlet portion beingconnected to a source of driving fluid and having a discharge mouth atits inner end opening into said chamber, said blade tips being of radialextent to terminate in the region of an extension of the axialcenterline of said discharge mouth when each blade tip is rotationallypositioned to be withing a plane normal of such extension, andregulating valve means in said inlet portion for reducing the pressureof the driving fluid within said inlet portion to produce a velocity ofcompressible driving fluid issuing through said discharge mouth intosaid chamber which is substantially greater than the peripheral velocityof said blade tips.
 5. In the turbine assembly as defined in claim 4wherein the tips of each blade when positioned to be within a planenormal to said extension of the axial centerline of said inlet portionterminates relative to said extension within a range extending from 0.10d inwardly of said extension to 0.02 d outwardly of said extension,wherein d is the diameter of said wheel portion.
 6. In the turbineassembly as defined in claim 5 wherein the velocity of said drivingfluid issuing through said discharge mouth is in the order of one andone-half to three times greater than the peripheral velocity of saidblade tips.